The invention relates to a height-adjustable support for semitrailers.
Supports of this type, usually arranged in pairs, are arranged in the front region of the semitrailer. A respective supporting foot with a foot plate, on which at least one rolling element rolls, is situated at the lower end of the extendible inner support tubes. The supports are used whenever the semitrailer is parked separately from the articulated lorry. In the case of the semitrailers which are prevalent nowadays and have air-sprung axles, the axle region may drop during relatively long parked periods because of pressure losses in the air spring bellows. In this case, with the axle assembly generally braked during parking, the semitrailer is subjected to a longitudinal thrust forwards, which the foot plates of the support are incapable of following because of adherence to the ground. In this situation, the supports with rigid foot plates would be exposed to a high flexural and buckling stress which might result in them being damaged. In order to avoid this, the said rolling elements act in a thrust-compensating manner on the foot plates, i.e. the supports move forwards on the foot plate by the rolling elements rolling out of the central position. When the load on the supports is removed again during coupling-on of the semitrailer, spring elements ensure that the foot plates are returned again into the central position, i.e. symmetrically to the particular support axis.
A support of the generic type is known from EP 0 886 592 B1, with a rolling element being provided in the foot region, and wire cables and compression springs serving to fasten and reset the foot plate being proposed. A configuration of this type has a large number of parts. And, in this case, there is no further attachment means for the foot plate.
DE 40 03 414 C2, the supporting foot is of a what is referred to as a telescopic supporting device for semitrailers which a rolling segment as a cut-out opening of a hollow cylinder with a partially cylindrical convex surface as rolling surface, the convex surface having slots which extend in the circumferential direction and through which helical springs are passed, of which one is fastened at one end at the front of the foot plate and at the other end at the front of the support tube and the other is fastened at one end at the rear of the foot plate and at the other end at the rear of the support tube. In the direction of the end side, the helical springs are arranged such that they are exposed centrally with respect to the foot plate and are therefore permanently exposed without protection to the weather, which may result in corrosion damage and cause malfunctions. In this case the width of the rolling segment exceeds the width of the support and, due to the unfavourably great height of this supporting foot and the arrangement of its pivot axle, necessarily on the lowermost end region of the inner support tube, a semitrailer support provided in such a manner obtains a disadvantageous, large construction height. In addition, this supporting foot is pivotable only in one plane and cannot compensate in the transverse direction for any unevennesses of the ground, which may result in overstressing of the material in the case of uneven parking surfaces. In addition, after its suspension means are released, a foot of this type could be completely lost.
It is an object of the invention to provide a height-adjustable support of the type of construction referred to above, wherein the foot region of which, while retaining the smallest possible construction height with resetting elements arranged in a manner protected from the weather, has protected means of suspending the foot plate and causes less structural outlay.